The formation of modern integrated circuit elements often includes chemical etch processes where various chemicals react with materials in an integrated architecture being constructed to remove portions of the materials. In these processes, certain materials are often used to protect portions of the device from chemicals being used to form other portions of the device. In these processes, developers utilize the selective nature of certain processes to erode one type of material and leave another type of material substantially unaffected. In this context, silicon nitride is often used as an etch stop for chemical etching processes used to etch silicon dioxide layers. By using silicon nitride layers as an etch stop, device architectures can be compactly spaced and overall device density can be increased.
A significant problem arises, however, when silicon nitride etch stop layers are used with flash memory or electrically erasable programmable read only memory (EEPROM) or UV EPROM devices. These devices typically utilize a floating gate that stores charge representative of data stored by the memory device. This charge is placed on the floating gate through operations that result in charge injection onto the floating gate. The charge is removed from the gate electrically or the memory cell is erased by exposing the device to ultraviolet radiation for a sufficient period of time. If the floating gate is covered by a silicon nitride layer, the floating gate will either not be able to be erased or the time period required to erase the floating gate will be dramatically increased, thereby reducing the effectiveness of the device.